Method and apparatus for conversion of organic reactants



April 26, 1960 .1.L. woRTH 2,934,495

METHOD AND APPARATUS FOR CONVERSION OF ORGANIC REACTANTS Filed Aug. 22,1958 3 Sheets-Sheet 1 Fig. /24

,t 23- l :I /j/ /l Il E j?? w g N /ll h l u l U -lO 'I l \73 INVEMOR.JOHN L. WORTH ATTORNEY April 26, 1960 J. WORTH 2,934,495

METHOD AND APPARATUS FOR CONVERSION oF ORGANIC REAcTANTs Fig. 2

INVENTOR. JOHN L. WORTH Y ATTORNEY April 26, 1960 J. L woRTH f 2,934,495

METHOD AND APPARATUS Fora coNvERsIoN oF ORGANIC AREAcTANT's Filed Aug.22, 1958 3 Sheets-Sheet 3 `'le I 3 IL- l INVET OR.

JOHN L. WORTH BYQaLzv, SFJQ@ ATTORNEY METHOD AND APPARATUS FORCONVERSION F ORGANIC REACTANTS John L. Worth, Wilmington, Del., assignerto Sun Oil Company, Philadelphia, Pa., a corporation of New JerseyApplication August 22, 1958, Serial No. 756,721

11 Claims. (Cl. 208-176) In United States Patent No. 2,704,741, issuedMarch 22, 1955, there is illustrated and described a novel type ofconverter in which iluid organic reactants are converted to otherorganic products by contact with a catalyst, and with which thecatalyst, by contact with other lluids, is periodically regenerated forcontact with later supplies of duid organic reactants. The inventiondescribed in that patent is especially applicable, though not limited,to conversion by -cat-alysis of higher hydrocarbons to mainly lowerboiling hydrocarbons, as in the well known petroleum oil crackingplants.

In this illustrative process, after such catalytic conversion, thecatalyst is purged by a suitable iluid, then regenerated by a suitablereactant, and again purged by `a suitable fluid, thus completing thecycle and reconditioning the catalyst for conversion of higher boilinghydrocarbons to mainly lower boiling hydrocarbons.

This process has been widely used commercially for many years, and hasbeen practiced in what are known as Athe iixed bed process, the movingbed process and the ilu-id catalyst pro-cess.

The converter' disclosed in said patent is of a type entirely differentfrom those in commercial use and different also other proposedconverters in that it embodies cert-ain features of novelty andimportance that adapt it to successful commercial use.

rhe subject matter of this application is an improveent on the type ofconverter disclosed in said patent. Such converter comprises a xed outercylindrical casing, a ixed inner cylindrical casing, `an annularrtatable reaction vessel between the two casings and spaced from both toform inner and outer circumferential spaces, partitions in the innercasing dividing its interior into sections, vertically andcircumferentially extending inner and outer seals between the rotatablereaction vessel and the inner and outercasing, the inner seals dividingthe inner circumferential space into independent arcuate spacescommunicating with the respective sections, lthe outer seals dividingthe outer circumferential space into independent arcuate spaces pairedwith the inner independent arcuate spaces, and a multitude ofcatalyst-containing compartments, preferably but not necessarily in theform of tubes, extending radially or transversely lthrough the reactionvessel and having inner inlets and outer outlets which, in the rotationof the reaction vessel, alford communication between successive pairs ofinner and outer arcuate spaces.

Inthis converter, fluid organic reactants are introduced into at leastone of the inner arcuate spaces, and are passed therefrom through thecatalyst-containing compartments. Upon contact with the catalyst, thefluid organic reactants are converted to other organic products, whichemerge from the catalyst-containing compartments into the outer `arcuatespaces, and are subsequently removed therefrom. This process iscontinuous, and during the continuous passage of the iiuid organicreactant, the annular rotatable reaction vessel is continuously rotated,so that additional catalyst-containing compartments are brought intocommunication with the inner arcuate space containing the fluid organicreactant, while those in communication with this inner arcuate space aremoved to communication with the succeeding arcuate space. In theconversion of higher boiling hydrocarbons to lower boiling hydrocarbons,a purging fluid, such las steam, is introduced into the succeeding innerarcuate space, in order `to purge converted and unconverted iluidreactants from the catalystcontaining compartments. The next innerarcuate space contains a regenerating medium, such as high temperatureair, to burn off deposited coke and prepare the catalyst tor additionalcontacting by iluid organic reactants. This is yfollowed by anotherinner arcuate space which supplies additional purging duid to removeproducts of the regeneration.

lt has been found that ya relatively large volume of high temperature,e.g., 900 F., air is required to insure adequate combustion of thedeposited coke during the regeneration portion of the cycle, withoutoverheating of the catalyst. Generally the catalyst cannot be exposed totemperatures above about l200 F., since higher temperatures causedeactivation of the catalyst. Furthermore, relatively high temperatureair, e.g., at least about 900 F. must be used in order to initiate andinsure substantially complete combustion of the deposited coke. T heyallowable temperature differential between the inlet air and eliiuentair containing gaseous regeneration products is therefore limited toabout 300 F., and relatively large quantities of air are required tomaintain ,the temperature differential within this range. Theillustrative catalytic cracking process is exothermic overall(hydrocarbon conversion plus catalyst regeneration), consequently alarge amount of heat m-us-t be removed in order to maintain the heatbalance of the converter. In many instances the capacity of theconverter is limited by the amount of heat which can be removed, Le.,the amount of air which can be used for cooling and regeneration.

A method has now been discovered whereby inlet air at a much lowertemperature may be used, thus increasing the hea-t removal per pound ofair, and resulting in a considerable reduction in the amount of airrequired for regeneration. This is achieved by providing an addi-Itional inner arcuate space in the fixed inner cylindrical casing, thisadditional inner arcuate space being situated between the inner arcuatespace for the first purging huid and the inner arcuate space whichsupplies the regenerating medium, such as air. is used, and is passedthrough the rotating catalyst `bed and into the outer arcuate spaceprovided for the removal of the air containing gaseous regenerationproducts. This eliiiuent is not removed, however, but is again passedthrough the rotating catalyst bed and into the additional inner yarcuatespace, from which it is exhausted. Thus this reverse flow of air servesto initiate combustion Vof the deposited coke, and the combustion iscontinued during contacting with the relatively low temperature air onits first pass through the catalyst.

Relatively low temperature air on line 2-2 of Figure l.

Referring now to Figure 1, indicates an outer cylindrical casing whichis suitably xed, as by ilanging, to a supporting head 11. The casing 10is made pressure ,tight and encloses a vessel which contains thecatalyst or contact material as well as the apparatus forming the ,fluidcompartments for the supply of the different startving uids to thevessel and the removal of different prod- `ucts from the vessel and alsosome of the elements for .eifecting rotation of the vessel.

The vessel 12 which contains the catalyst or contact material is annularin shape and formed by an outer cylindrical sidewall 13 and an innercylindrical sidewall 14 which are concentric one with another and areinterconnected by annular end plates 15 and 16, respectively.

Vessel 12 is divided by vertical partitions 17, as more clearly seen inFigure 2, into a plurality of transversely 4extending contact materialchambers 18. Each of these contact material chambers is substantiallyfilled with a contact material M.

The vessel 12 and associated elements form an assembly Which is disposedwithin the casing 10 to provide an outer annular space 20 with itssidewall, a lower space 21, with the supporting head 11, and an enlargedspace 22 with the upper end of the casing and with the inner sidewall.14 of the reaction vessel. A set of rollers 23 are provided within thelower space 21 to rotatably support the vessel 12 which is driven by amotor 24 suitably connected through a pinion 27 to a ring-gear 25,formed on extension 26, at the upper end of the reaction vessel sidewall13.

The space is divided by circumferential seals, comprising a pair ofcircular blocks 31 and 32 positioned in spaced relation to formtherebetween an outer annular fluid zone 33 while the space 22 issimilarly divided by circumferential seals comprising circular blocks 29and 30, positioned in -spaced relation to form an inner annular uid zone34 therebetween. The Huid zones 33 and 34 communicate with each otherthrough apertures 35 and 36 formed in the vessels outer and inner walls,respectively, so that fluid reactants supplied to one of the zones maypass through the contact material M in the vessel 12 and the productsthereof removed from the other zone.

In Figure 2 the outer fluid zone 33 is further divided by a plurality ofvertical seals, comprising spaced elongated blocks 40, to form spacedouter arcuate compartments therein, and the inner iluid zone 34 isdivided by vertical seals 41, comprising similar blocks, to form spacedinner arcuate compartments.

Since the function of the circumferential and vertical seals is toprovide a set of inner iluid compartments which are separate andindependent and a set of outer uid compartments which are separate andindependent, the particular construction and manner of joining thecooperating seals may be such as to eifect this result and hence nospecific construction of the seals is considered necessary. However, anoperative seal is described in the hereinbefore referred to Patent No.2,704,741, and other operative seals are described in United StatesPatent Nos. 2,715,567; 2,715,568; 2,715,569; and 2,715,570.

An inner cylindrical casing 45 having end walls 46 and 47 is positionedwithin the enlarged space 22 concentrically with casing 10, and isprovided with a plurality of radial partitions 50, 51, 52, 53 and 54,shown ,i 5' magazines.

clearly in Fig. 2, which extend between the ends 46 and 47 of the innercasing and have their inner edges secured to a central post 49 and theirouter edges secured to a central post 49 and their outer edges securedto the inner wall of casing 45, dividing the casing into independentsections. Each radial partition is aligned with an inner vertical sealas indicated, in `order to divide the casing into a number of sectionsequal to the number of these seals. Between the adjacent partitions,openings 55, 56, 57, 58 and 59 are provided in the casing 45, placingthe sections in communication with inner compartments 61, 62, 63,64 andformed in the inner fluid zone 34 between the vertical seals 41. Innercompartments 61, 62, 63, 64 and `65 will be in communication throughopenings 35 and 36 with outer compartments 66, 67, 68 and 69, for-medbetween outer vertical seals 40. Note that five inner compartments areprovided, whereas there are only four outer compartments. Innercom-partments 61, 62 and 65 form pairs of compartments with outercompartments 66,67 and 69, respectively, whereas outer compartment 68 issufciently long to be opposite both the inner compartments 63 and 64.

Conduits indicated at 70, 71, 72, 73 and 74 are pro` vided within thedilferent sections formed in casing 4S for supplying uids to or removingfluids from inner compartments 61, 62, 63, 64 and 65, respectively, andconduits 75, 76 and 77 are provided for supplying fluids to or removingfluids from outer compartments 66, 67 and 69, respectively.

In order to prevent the different iluids in adjacent inner compartmentsfrom entering any one catalyst chamber vat the same time the innervertical seals will be at least as wide and preferably slightly widerthan the inner end of each of the transversely extending contactmaterial chambers 18, and similarly the outer vertical seals will be atleast as wide and preferably slightly wider than the outer end of eachof the transversely extending contact material chambers 18. From aninspection of Figure 2 it will be seen that as the vessel 12 is rotatedthe seals 40 and 41 will cover the openings 35 and 36 of one chamber 1Sso that any chamber 18 formed between the adjacent vertical partitions17 can only be in communication with one pair of cooperating inner andouter uid compartments at any one time, since the vertical seals will atall times block o the fluids in the next adjacent pair of cooperatingcompartments. In other words, each contact material chamber will becompletely blocked off before it is advanced or rotated to be incommunication with the next pair of cooperating compartments.

The circumferential and vertical seals will preferably be madestationary with the stationary inner and outer casings 45 and 10although if desired they may be arranged to rotate with the walls ofvessel v12. In order to reduce frictional contact between the relativelyrotating elements of the apparatus a suitable lubricating medium may beused and also the seals may be so designed as to take into account anystrains or stresses due to expansion or contraction which may be causedby temperature variations during the operation of the apparatus.

The illustrated and described apparatus, although applicable generallyto processes utilizing in succession a plurality of different iluidsthat contact with a catalyst Or other contact material, such operationcomprising a series of steps in sequence which are repeatedindefinitely, lends itself particularly to the cracking or othertreatment of petroleum hydrocarbons. For example, in the so-calledfixed-bed catalytic plants, when applied to such cracking, a stationarycatalyst mass is contacted, in sequence, rst with a hydrocarbon iluid toform other and mainly lower boiling hydrocarbons; second, with a purgemedium, such as steam, to remove from the catalyst hydrocarbon materialremaining therein; third, with a regenerating medium, such as air, toremove carbon deposited on the catalyst during the rst step; and fourth,

contacted simultaneously with the above-mentioned iluids which will bedistributed radially across the chambers of each group trom either theinner or outer set of compartments. For example, in hydrocarbonconversion, oil vapors are supplied to compartment 61 for passagethrough the group of chambers located between compartments 61 and 66. Aiirst purge iluid, eg., steam, is supplied to compartment 62 for passagethrough -the group of chambers located between compartments 62 and 67.Up to this point, the process is the ysame as that of the aforementionedPatent No. 2,704,741. According to the present invention, however,regenertaion fluid, e.g., air, is supplied to compartment 64 for passagethrough the group of chambers located between compartments 64 and 68.The regeneration fluid, having passed through the catalyst bed intocompartment 68, is now returned through the group of chambers locatedbetween compartments 68 and 63, and is removed from compartment 63through opening 57 and conduit 72. A second purge fluid is supplied tocompartment 65 for passage through the group of chambers located betweencompartments 65 and 69. The vessel 12 is rotated at some predeterminedrate, and for the purpose of lthis description, in a` clockwisedirection, so that the chambers of each group will successively advanceuntil the contact material in each chamber has been contacted with eachof the different iluids, and then la new cycle of operation will begin.

According to the present invention a relatively low temperatureregenerating fluid is admitted to compartment 64. Air is the preferredregenerating Huid, although other oxygen-containing gases, preferablycontaining at least 10% oxygen by weight, whose other components do notreact with the contact material may also be used. The regenerating iuidis introduced at a temperature of from atmospheric up to about 700 F.,and preferably at from about 200 F. to about 500 F. During passage fromcompartment 6d to compartment 68, the air is heated by the hot contactmaterial, and in turn serves to cool the contact material to someextent. In addition, oxygen in the air supports combustion of any cokeremaining on the Contact material. The air Vis supplied at a space ratesufficient to lower the temperature of the contact material by apredetermined amount, and also to Supply suiicient oxygen forsubstantially complete combustion of the deposited coke.

Upon passage into compartment 68, the heated air is passed through thegroup of chambers located between compartments 68 and 63. During itsini-tial passage through the contact material, the air has been heatedsuiiciently to initiate combustion of the deposited coke during itssecond passage. The air is then further heated by the combustion of thecoke during this second passage, and passes `into compartment 63 at atemperature preferably from about l150 F. to 1200 F. Under certainconditions lower temperatures, down to about 10.00 F., may be desirable,and higher temperatures may be used where the particular contactmaterial and materials of construction allow it. Thus, by theimprovement of this invention, the temperature differential of theregeneration fluid is increased from the former 300 F. maximum to 1000F. or more. Furthermore, the oxygen in the regeneration iluid isutilized more eciently. Formerly only from about 5% to about 20% of theoxygen in air ywas consumed in combustion of the coke, whereas by theimprovement of this invention up to 50% or more of the oxygen may beutilized.

The following comparison of the heat removal obtained by the previoussingle pass method and that obtained by the present double pass methodeffectively illustrates the superiority of the present method in thatrespect:

Air Temperature Heat Removal,

F. B.t.u./# Air Outlet Inlet Single Double Pass Pass The single passprocess cannot be operated at inlet air temperatures substantially below900 F., since such lower temperatures will not initiate combustion ofthe coke at a practical rate.

Another important #advantage of the present system is that more uniformcatalyst bed temperatures are maintained, since in one pass of the air,the cooler air contacts the radially vinward portion of the catalyst,and iu the other pass the cooler air contacts the radially outwardportion ofthe catalyst. This allows the maintenance of a higher averagetemperature in the catalyst bed without fear of overheating portions ofthe catalyst, and consequently results in a more eflicient use of theregenera- -tion zone, since more coke can be burned per unit volume.

Figure 3 depicts another embodiment of the invention, wherein theregeneration iluid irstcontacts the contact material in the center ofthe regeneration zone, then a portion of the heated air is returnedthrough the catalyst bed as in theembodiment of Figure 2, While theremainder of the heated regeneration fluid is returned on .the otherside of the regeneration iluid inlet, so that the contact material isswept by hot gases immediately betfore leaving the regeneration zone.Thus in Figure 3 regeneration iuid is supplied through conduit 78 andopening 80 in casing 45 to compartment 82 and is passed through thegroup of chambers 1S located between compartments 82 and 68. A portionis then passed from compartment 63 through the group of chambers locatedbetween compartments 68 and 84 into compartment 84 and thence throughopening 86 and out conduit 88. Another portion of the regenerating fluidis passed from compartment 68 through the group of chambers locatedbetween compartments 68 and 90 and thence through opening 92 and outconduit 83. Partition v94 separates the air inlet section from the airoutlet section. In some instances it may be `desirable to also separatethe eluent regeneration uid from compartments 84 and 90 and pass itthrough separate outlet conduits. Such structure would allow bettercontrol of the regeneration step.

This modification provides greater ilexibility than that of Figure 2, inthat the temperature of the contact material leaving the regenerationzone may be at a higher and more uniform temperature.

An additional advantage that results from the use of either of themodifications of this invention is that superheated steam could be usedfor purging the regeneration products from` the contact mass. At presentit is necessary to use low pressure saturated steam, since the purgematerial is also used to remove some heat from the contact mass and toreduce the range of temperatures prevailing in the contact mass. Hightemperature, superheated steam purges much more efficiently than doeslow pressure steam.

Many modications of this invention will be apparent to those skilled inthe arts. Several modiiications of the '7 reactor are described in theaforementioned patents', and it is obvious that the present inventioncan easily be applied to any of the modifications of the reactor whicharedescribed in those patents. The invention is therefore limited 'onlyas set forth in the appended claims.

The invention claimed is:

1. In' a process which comprises rotating an annular reactor containinggroups of contac-t material chambers, alternately passing a, fluidorganic reactant and a regenerating fluid radially through each of saidgroups of contact material chambers, and passing a purging mediumthrough each group of chambers after each passage of fluid reactant andafter each passage of regenerating uid, the improvement which comprisesintroducing said regenerating fluid at a temperature insufficient toinitiate combustion, and returning at least a portion of theregenerating fluid, which has been heated during the firstnamed passingto a temperature sufficient to initiate combustion, radially throughsaid groups of contact material chambers after the passage of said fluidorganicrreactant and said purging medium and before the initial passageof said regenerating fluid.`

2. In -a process for converting hydrocarbons which comprises rotating anannular reactor containing groups of contact material chambers,alternately passing a uid hydrocarbon reactant and contact materialregeneratlng 'fluid from separate compartments of a fixed inner iiuidzone through each of said groups of contact material chambers and intoseparate compartments of a fixed outer fluid zone, removing fluidhydrocarbon conversion products from said fixed outer fluid zone, andpassing a purging medium through each group of chambers -after eachpassage of fluid reactant and after each passage of regenerating fluid,the improvement which comprises 4introducing said regenerating fluid ata temperature insufficient to initiate combustion, and passing at leasta portion of the contact material regenerating fluid, which has beenheated during the first-named passing to a temperature suicient toinitiate combustion, in said ixed outer nid zone back through the groupsof contact material chambers after the passage of said fluid hydrocarbonreactant and said purging medium and before the initial passage of saidregenerating fluid.

3. A process as dened by claim 2 wherein said regenerating fluid is air.4. A process for converting hydrocarbons which comprises rotating anannular reactor containing groups of contact material containingchambers, introducing a uid hydrocarbon reactant into a compartment of axed inneruid zone within the inner wall of said annular reactor,introducing a regenerating fluid at a temperature in the range from roomtemperature to 700 F. into another compartment of said fixed inner`fluid zone, successively contacting the contact material in each ofsaid groups of chambers alternately with the fluid hydrocarbon reactantand the regenerating uid by passing each of said fluids radiallyoutwardly through said groups of chambers into separate compartments ofa fixed outer fluid zone, whereby said uid hydrocarbon reactant isrconverted to hydrocarbon conversion products and said regeneratingfluid is heated to a temperature of at least 900 F., removing saidhydrocarbon conversion products from one of said compartments, passingpurging medium through each group of chambers after each passage of uidreactant and after each passage of regenerating fluid, and passing atleast a portion of said regenerating fluid radially inwardly throughsaid groups of contact material containing chambers after eachcontacting of rsaid contact material with said fluid hydrocarbonreactant 'and said purging medium and before each contacting of saidcontact material with the first-named regenerating iuid.

5. A process as defined by claim 4 wherein a portion of said heatedregenerating uid is passed radially in :wardly through said groups ofcontact material contain- 8 ing chambers after each contacting off saidcontact material with the first-named regenerating fluid and beforeeach. contacting of said contact material with said fluid hydrocarbonreactant.

6.V A rotary converter for iluid organic reactants which comprises afixed outer cylindrical casing, a fixed inner cylindrical casing, anannular revoluble reaction vessel between the inner and outer casingsand spaced from .both to Yform inner and outer'annular uid zones, aplurality of transversely extending contact material chambers in said4reaction vessel, means for revolving said reaction Vessel, meansdividing said inner annular fluid zone into a plurality of spaced innerarcuate compartments, means dividing said outer annular fluid zone intoat least one less spaced outer arcuate compartment, each `except one ofsaid outer arcuate compartments being radially opposite one innerarcuate compartment, said one outer arcuate compartment being radiallyopposite the remainder of said inner' arcuate compartments, `means forsupplying fluids to and removing uids from each of said inner arcuatecompartments, and means for supplying fluids to and removing fluids fromeach of said outer arcuate compartments except said one.

7. A. rotary converter for fluid organic reactants which comprises a xedouter cylindrical casing, a fixed inner cylindrical casing, an annularrevoluble reaction vessel between the inner and outer casings and spacedfrom both to form inner and outer annular fluid zones, a plurality oftransversely extending contact material chambers in said reactionvessel, means for revolving said reaction vessel, a plurality of spacedinner arcuate compartments in said inner annular fluid Zone, at leastone less spaced outer arcuate compartment in said outer annular uidzone, each except one of which is radially opposite one inner arcuatecompartment, said one outer arcuate compartment being radially oppositethe remainder of said inner arcuate compartments, means for supplyingfluids to and removing fluids from each of said inner arcuatecompartments, and means for supplying fluids to and removing fluids fromeach of saidouter arcuate compartments except said one.

8. A rotary converter as dened by claim 7 which has one less outerarcuate compartment than inner arcuate compartments.

9. A rotary converter as defined by claim 7 which has two less outerarcuate compartments than inner arcuate compartments.

l0. In a rotary converter for liuid organic reactants which comprises afixed outer cylindrical casing, a fixed inner cylindrical casing, anannular revoluble reaction vessel between the inner and outer casings, aplurality of transversely extending contact material chambers in saidreaction vessel, means for revolving said reaction vessel, and means foralternately passing a fluid organic reactant and a regenerating uidthrough each of said transversely extending contact material chambers,the improvement which comprises means for repassing said regeneratinguid through each of said contact material chambers after the passage ofsaid duid organic reactant and before the initial passage of saidregenerating uid, said means for .repassing comprising a compartment inthe outer casing, which compartment is in gaseous communication withsaid chambers only, and is adapted to receive regenerating iiuid from acompartment of said inner casing through said chambers and to returnregenerating fluid to another compartment of the inner casing throughsaid chambers.

1l. A rotary converter which comprises a revoluble reaction vesselhaving a plurality of chambers therein, a first set of fixedcompartments in gaseous communication with said chambers, a second setof fixed compartments in gaseous communication with said chambers, saidreaction vessel being disposed between the sets of compartments, thesecond set of compartments containing at least one less compartment thanthe rst set, each except one of the second set of compartments beingopposite one compartment of the rst set, and said one compartment of thesecond set being opposite a plurality of compartments of the first set,means for supplying fluids to and removing fluids from each compartmentof the rst set, and means for supplying fluids to and removing uids fromeach compartment ofthe second set except said one.

References Cited in the le of this patent UNITED STATES PATENTS CampbellDec. 8, 1942 Crowley Apr. 5, 1949 Thayer Mar. 22, 1955 Thayer Mar. 27,1956

1. IN A PROCESS WHICH COMPRISES ROTATING AN ANNULAR REACTOR CONTAININGGROUPS OF CONTACT MATERIAL CHAMBERS, ALTERNATELY PASSING A FLUID ORGANICREACTANT AND A REGENERATING FLUID RADIALLY THROUGH EACH OF SAID GROUPSOF CONTACT MATERIAL CHAMBERS, AND PASSING A PURGING MEDIUM THROUGH EACHGROUP OF CHAMBERS AFTER EACH PASSAGE OF FLUID REACTANT AND AFTER EACHPASSAGE OF REGENERATING FLUID, THE IMPROVEMENT WHICH COMPRISESINTRODUCING SAID REGENERATING FLUID AT A TEMPERATURE INSUFFICIENT TOINITIATE COMBUSTION, AND RETURNING AT LEAST A PORTION OF THEREGENERATING FLUID, WHICH HAS BEEN HEATED DURING THE FIRSTNAMED PASSINGTO A TEMPERATURE SUFFICIENT TO INITIATE COMBUSTION, RAIDALLY THROUGHSAID GROUPS OF CONTACT MATERIAL CHAMBERS AFTER THE PASSAGE OF SAID FLUIDORGANIC REACTANT AND SAID PURGING MEDIUM AND BEFORE THE INITIAL PASSAGEOF SAID REGENERATING FLUID.